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Old Aug 6, 2003, 3:21 PM   #1
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Default DSLRs and Light Meters

Quick questions for all the experts out there...Do DSLRs measure light the same way regular film cameras do. ie...If I measure 8.0 @ 1/60 @ 400 on a light meter is that same for both digital and film cameras or is there is conversion factor?

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Old Aug 6, 2003, 4:28 PM   #2
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same thing as a reflective type meter. and with an expo disc a ambient light meter.
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Old Aug 6, 2003, 4:29 PM   #3
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Yes, ie no conversion factor needed!...

This is funny but I use my D7 WYSIWYG mode and it's realtime histogram as my lightmeter for nightshots on the 10D (it beats the heck out @ reviewing the pictures on the rear progressive display LCD) 8)
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Old Aug 6, 2003, 10:20 PM   #4
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I believe that the DSLRs are using the exact same part as similar models of SLR. I know Nikon and Canon reuse AF systems, I assume they also reuse the light meter.

For cost and inventory reasons, it only makes sense.

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Old Aug 6, 2003, 11:56 PM   #5
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Default Re: DSLRs and Light Meters

Quote:
Originally Posted by jazz
Do DSLRs measure light the same way regular film cameras do. ie...If I measure 8.0 @ 1/60 @ 400 on a light meter is that same for both digital and film cameras or is there is conversion factor?
The answer is both yes and no. There are two types of ambient light meters: reflective and incident. Reflective meters measure the intensity of the light reflected from an object. Since it does not know what the actual scene illumination is, a reflective light meter always assumes the area it sees has a 50% gray (or 18% reflectance). Virtually all on-board camera meters, whether it is a SLR, a D-SLR or a P&S, are reflective meters. This type has a problem: if one points a reflective meter to a white (resp., black) area, that area would be under- (resp., over-) exposed since it is treated as a 50% gray. On the other hand, an incident meter measures the intensity of incoming light, and the measurement is absolute (i.e., the meter knows what white and black are). Hence, it is more accurate. Consequently, while the reading is 8.0 @ 1/60 @ 400, it means two different things with reflective and incident meters: relative for reflective meters and absolute for incident meters. To convert a reflective meter to an incident one, use the reflective meter to read a 18% reflectance gray card, or buy an Expo/Disc @ http://www.expodisc.com/

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